1. Field of the Invention
The present invention relates generally to network concentrators and more particularly, to a method and apparatus for associating Data Terminal Elements to a port on a network concentrator.
2. Description of the Related Art
It is known in the art to interconnect Data Terminal Elements (DTEs) through a common communication cable. Such interconnection provides for enhancements such as simplified transfer of information, sharing of resources and distributed functionality. A configuration of interconnected DTEs that are within a close proximity, e.g. the same building, is known as a Local Area Network (or LAN). The physical manner in which the DTEs are interconnected is termed a LAN topology. Associated with a LAN topology is a protocol. A LAN protocol refers to the format in which data is transmitted and the rules by which Data In the network is transmitted and received.
One such LAN topology is a ring topology. In a ring topology, the DTEs are successively interconnected in a daisy chained fashion to form the ring. Data transmitted through the LAN will propagate around the ring and through each of the successive DTEs.
A common protocol used in a ring topology is a token passing protocol. In a token passing protocol a token is continuously transmitted around the ring. Whenever a DTE desires access to the network for transmission of data or some other function, the token is examined to determine if some other DTE has control of the network. Through a scheme of priorities and time sharing, the various DTEs are given control of, i.e. the ability to transmit data onto, the network.
A well known example of such a network with a ring topology utilizing a token passing protocol is the token-ring, which is embodied in the American National Standards Institute/Institute of Electrical and Electronics Engineers (ANSI/IEEE) 802.5 Token Passing Ring standard.
An example of a token ring network is provided with reference to FIG. 1 which illustrates a ring-shaped communications media 103 having coupled thereto a plurality of ring interface units 102. Each ring interface unit 102 may be coupled with a DTE 101. A further description of typical components of a token-based network may be found, for example, with reference to Madron, T.W., LANS Applications of IEEE/ANSI 802 Standards, John Wiley & Sons, 1989 at pg. 163.
More recently network concentrators (also termed intelligent hubs) have been provided in networks in order to provide for increased connectivity, internetworking, and network management. An example of such a concentrator is the LattisNet System 3000.TM. intelligent hub available from SynOptics Communications, Inc. of Santa Clara, Calif. In a system utilizing a concentrator, each DTE is coupled with the concentrator and the concentrator provides a common communication channel, or backplane, allowing for communication between the various DTEs. This type of network, when depicted graphically, can represent a star-like image and, thus, is often referred to as a star configured network.
FIG. 2 illustrates a network as may be configured utilizing a concentrator. As illustrated by FIG. 2, a network may comprise a plurality of concentrators, such as concentrators 201 and 202. Each concentrators may have a plurality of data terminals coupled with the concentrators, such as data terminals 221-223 which are coupled with concentrators 201 and data terminals 231-233 which are coupled with concentrators 202.
The data terminals are coupled with the concentrator through one or more host modules which are housed in the concentrator. For example, data terminals 221 and 222 are each coupled with host module 241 while data terminal 223 is coupled with host module 242. The host modules provide individual ports for coupling with the data terminals.
The host modules are each coupled with a backplane bus (not shown) in the concentrator to allow communication with a repeater module, for example, repeater module 214. The repeater module is used to amplify and retransmit message packets being transmitted within the concentrator. For example, DTE 221 may transmit a message. As has been discussed above, data terminals 222 and 223 will then examine the packet to determine if the destination address of the message indicates the message is to be processed.
In addition, the concentrator may comprise a bridge or router module such as module 211 of concentrator 201. The bridge or router module allows communication of messages between DTEs which may exist in other parts of the network. As can be seen with reference to FIG. 2, concentrator 201 and concentrator 202 are coupled in communication through bridge/router 211 which is on concentrator 201 and bridge/router 212 on concentrator 202 to allow messages to be communicated from DTEs 221-223 coupled with concentrator 201 to DTEs 231-233 coupled with concentrator 202.
Port-Station Association
In some instances, a single physical attachment to the network concentrator will allow a plurality of DTEs to be coupled into the network. For example, in the case of a remote bridge, the single remote bridge coupling may incorporate multiple DTEs coupled to the corresponding concentrator on the remote end of the bridge, to be coupled into the network. In a similar manner it would be desirable to allow more than one DTE to be coupled to a port on the network concentrator.
In order to maintain proper management and security of the network, a means for recognizing the physical connection, e.g. the port, to which a DTE is connected to the network, is necessary. Such a port/station association is important in the event one or more DTEs must be partitioned from the network. This may arise, for example in a situation where a particular DTE, or set of DTEs are deteriorating network performance through excessive use. Such an instance may arise if the DTEs are constantly transmitting data onto the network. In such a situation, it may be desirable to partition such offending DTEs off of the network.
A second instance may arise with respect to network security. For example, if a DTE is performing an unprivileged data access to/from another DTE, it may again be desirable to partition the offending DTE off the network.
The requirement of a port/station association may cause restrictions in the implementation of a network concentrator. For example, it is common for a concentrator to have a restriction where a port may only have one station connected to it. Further, the need for port/station association has often complicated the installation of new stations onto the network. Finally, it is desirable that such a means be dynamic, namely that the port/station association may occur while the network is in operation, rather, than being a static process (e.g. loading a pre-defined table).
Thus, it is a primary object of the present invention to provide a means by which stations may be dynamically associated to a particular port on a network concentrator which in turn would allow for multiple stations to be connected to a single port on a concentrator.